Neoadjuvant SABR for Renal Cell Carcinoma Inferior Vena Cava Tumor Thrombus—Safety Lead-in Results of a Phase 2 Trial

PurposeTo evaluate the feasibility, safety, oncologic outcomes, and immune effect of neoadjuvant stereotactic radiation (Neo-SAbR) followed by radical nephrectomy and thrombectomy (RN-IVCT).Methods and materialsThese are results from the safety lead-in portion of a single-arm phase 1 and 2 trial. Patients with kidney cancer (renal cell carcinoma [RCC]) and inferior vena cava (IVC) tumor thrombus (TT) underwent Neo-SAbR (40 Gy in 5 fractions) to the IVC-TT followed by open RN-IVCT. Absence of grade 4 to 5 adverse events (AEs) within 90 days of RN-IVCT was the primary endpoint. Exploratory studies included pathologic and immunologic alterations attributable to SAbR.ResultsSix patients were included in the final analysis. No grade 4 to 5 AEs were observed. A total of 81 AEs were reported within 90 days of surgery: 73% (59/81) were grade 1, 23% (19/81) were grade 2, and 4% (3/81) were grade 3. After a median follow-up of 24 months, all patients are alive. One patient developed de novo metastatic disease. Of 3 patients with metastasis at diagnosis, 1 had a complete and another had a partial abscopal response without the concurrent use of systemic therapy. Neo-SABR led to decreased Ki-67 and increased PD-L1 expression in the IVC-TT. Inflammatory cytokines and autoantibody titers reflecting better host immune status were observed in patients with nonprogressive disease.ConclusionsNeo-SAbR followed by RN-IVCT for RCC IVC-TT is feasible and safe. Favorable host immune environment correlated with abscopal response to SABR and RCC relapse-free survival, though direct causal relation to SABR has yet to be established

Phase II Trial of Sipuleucel-T and Stereotactic Ablative Body Radiation for Patients with Metastatic Castrate-Resistant Prostate Cancer

(1) We hypothesized that adding concurrent stereotactic ablative radiotherapy (SAbR) would increase the time to progression in patients with metastatic castrate-resistant prostate cancer (mCRPCA) treated with sipuleucel-T. (2) Patients with a history of prostate cancer (PC), radiographic evidence of metastatic disease, and rising prostate-specific antigen (PSA) > 0.2 ng/dL on castrate testosterone levels were enrolled in this single-arm phase II clinical trial and treated with sipuleucel-T and SAbR. The primary endpoint was time to progression (TTP). Cellular and humoral responses were measured using ELISpot and Luminex multiplex assays, respectively. (3) Twenty patients with mCRPC were enrolled and treated with SAbR to 1–3 sites. Treatment was well tolerated with 51, 8, and 4 treatment-related grade 1, 2, and 3 toxicities, respectively, and no grade 4 or 5 adverse events. At a median follow-up of 15.5 months, the median TTP was 11.2 weeks (95% CI; 6.8–14.0 weeks). Median OS was 76.8 weeks (95% CI; 41.6–130.8 weeks). This regimen induced both humoral and cellular immune responses. Baseline M-MDSC levels were elevated in mCRPC patients compared to healthy donors (p = 0.004) and a decline in M-MDSC was associated with biochemical response (p = 0.044). Responders had lower baseline uric acid levels (p = 0.05). No clear correlation with radiographic response was observed. (4) While the regimen was safe, the PC-antigen-specific immune response induced by SAbR did not yield a synergistic clinical benefit for patients treated with sipuleucel-T compared to the historically reported outcomes